The Earthquake Engineering Online Archive

Seismic risk analysis for a site and a metropolitan area

Oliveira, Carlos S.

UCB/EERC-75/03, Earthquake Engineering Research Center, University of California, Berkeley, 1975-08, 198 pages (390/O42/1975)

A general probabilistic methodology for handling the concept of seismic risk analysis as a measure of losses of life and property suffered by a metropolitan area during a given period of time is presented. The advantages of developing this kind of model are analyzed for those cases where decision-making involves global risks. Earthquake generation is considered as a stochastic point process random in time, space and magnitude and the earthquake ground motion is considered as a continuous time parameter stochastic process. Attenuation laws include, in a deterministic way, the changes in the predominant period of ground motion with distance and magnitude and, in a random way, an error term. The final probability distribution of maximum response of a one-degree-of-freedom system considering both the randomness of intensity and the randomness of response is studied. The damage ratio function is the fundamental unit that induces material and life losses through a metropolitan area after making use of local and spatial morphologies. It is based on the response of a building represented by a one degree-of-freedom with resisting properties characterized by two random variables, yield and collapse. Direct and indirect losses are related to the damage ratio and assembled together in an individual loss function. Its integration over an entire metropolitan area gives the global loss function which is then corrected to include the global consequences of earthquakes. A general discussion on the analysis of decision-making applied to a metropolitan area is made and emphasis is given to the following points, among others: planning of a new town, identifications of zones of higher potential damage, construction policy after the occurrence of a destructive earthquake and risk for lifeline systems.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-75-03.pdf (9 MB)